scholarly journals The rosy locus in Drosophila melanogaster: xanthine dehydrogenase and eye pigments.

Genetics ◽  
1991 ◽  
Vol 129 (4) ◽  
pp. 1099-1109 ◽  
Author(s):  
A G Reaume ◽  
D A Knecht ◽  
A Chovnick
Keyword(s):  
Drosophila Melanogaster ◽  
Structural Integrity ◽  
Present Report ◽  
Specific Interaction ◽  
Pigment Granule ◽  
Ultrastructural Localization ◽  
Xanthine Dehydrogenase ◽  
Pigment Formation ◽  
Antibody Staining ◽  
Pigment Granules

Abstract The rosy gene in Drosophila melanogaster codes for the enzyme xanthine dehydrogenase (XDH). Mutants that have no enzyme activity are characterized by a brownish eye color phenotype reflecting a deficiency in the red eye pigment. Xanthine dehydrogenase is not synthesized in the eye, but rather is transported there. The present report describes the ultrastructural localization of XDH in the Drosophila eye. Three lines of evidence are presented demonstrating that XDH is sequestered within specific vacuoles, the type II pigment granules. Histochemical and antibody staining of frozen sections, as well as thin layer chromatography studies of several adult genotypes serve to examine some of the factors and genic interactions that may be involved in transport of XDH, and in eye pigment formation. While a specific function for XDH in the synthesis of the red, pteridine eye pigments remains unknown, these studies present evidence that: (1) the incorporation of XDH into the pigment granules requires specific interaction between a normal XDH molecule and one or more transport proteins; (2) the structural integrity of the pigment granule itself is dependent upon the presence of a normal balance of eye pigments, a notion advanced earlier.

scholarly journals ORGANIZATION OF THE ROSY LOCUS IN DROSOPHILA MELANOGASTER: FURTHER EVIDENCE IN SUPPORT OF A CIS-ACTING CONTROL ELEMENT ADJACENT TO THE XANTHINE DEHYDROGENASE STRUCTURAL ELEMENT

Genetics ◽  
1979 ◽  
Vol 91 (2) ◽  
pp. 275-293
Author(s):  
M McCarron ◽  
J O'Donnell ◽  
A Chovnick ◽  
B S Bhullar ◽  
J Hewitt ◽  
...  
Keyword(s):  
Drosophila Melanogaster ◽  
Control Region ◽  
Large Scale ◽  
Present Report ◽  
Xanthine Dehydrogenase ◽  
Control Element ◽  
Genetic Dissection ◽  
Structural Element ◽  
Cis Acting ◽  
A Site

ABSTRACT The present report summarizes our recent progress in the genetic dissection of an elementary genetic unit in a higher organism, the rosy locus (ry: 3-52.0) in Drosophila melanogaster. Pursuing the hypothesis that the rosy locus includes a noncoding control region, as well as a structural element coding for the xanthine dehydrogenase (XDH) peptide, experiments are described that characterize and map a rosy locus variant associated with much lower than normal levels of XDH activity. Experiments are described that fail to relate this phenotype to alteration in the structure of the XDH peptide, but clearly associate this character with variation in number of molecules of XDH per fly. Large-scale fine-structure recombination experiments locate the genetic basis for this variation in the number of molecules of XDH per fly to a site immediately to the left of the XDH structural element within a region previously designated as the XDH control element. Moreover, experiments clearly separate this "underproducer" variant site from a previously described "overproducer" site within the control region. Examination of enzyme activity in electrophoretic gels of appropriate heterozygous genotypes demonstrates the cis-acting nature of this variation in the number of molecules of XDH. A revision of the map of the rosy locus, structural and control elements is presented in light of the additional mapping data now available.

scholarly journals Functional Significance of the Crystal Cells in the Larva of Drosophila melanogaster

1959 ◽  
Vol 5 (2) ◽  
pp. 235-240 ◽  
Author(s):  
M. T. M. Rizki ◽  
Rose M. Rizki
Keyword(s):  
Drosophila Melanogaster ◽  
Blood Cells ◽  
Structural Integrity ◽  
Present Report ◽  
Enzymatic Reaction ◽  
Humoral Factors ◽  
To Come ◽  
Crystal Cells

Cytoplasmic crystalline inclusions are found in some larval haemocytes of Drosophila melanogaster. Blackening can be experimentally induced in these cells, and previously it was suggested that either the substrate or enzyme for the tyrosine-tyrosinase system leading to melanin production in Drosophila larvae is found in these inclusions in the crystal cells. The present report is an attempt to further localize the enzyme and substrate. Larvae have been fed on food containing α-C14-tyrosine and autoradiographs of the blood cells taken from these larvae subsequently prepared. The C14 activity in the crystal cells is restricted to the crystal inclusions in the cells and is significantly higher than that found in the other type of haemocytes, the plasmatocytes. When samples of the blood cells are incubated in DOPA solution, the extra-crystalline cytoplasm becomes blackened while the crystals themselves remain colorless. These observations are consistent with the hypothesis that the substrate is localized in the crystal inclusions whereas enzyme is found in the surrounding cytoplasm. An in vivo structural isolation would serve to separate enzyme and substrate rather than an inhibition by dehydrogenases as postulated by previous authors. In vitro examination with the phase microscope has shown that the crystal cells rupture easily and the crystals dissolve in the haemolymph. Therefore any treatment which tends to disrupt the structural integrity of the cell will allow the enzyme and substrate to come together. Humoral factors preceding metamorphosis might account for the in vivo release of the enzymatic reaction by initially altering the permeability of the cell.

scholarly journals INTRACISTRONIC MAPPING OF ELECTROPHORETIC SITES IN DROSOPHILA MELANOGASTER: FIDELITY OF INFORMATION TRANSFER BY GENE CONVERSION

Genetics ◽  
1974 ◽  
Vol 76 (2) ◽  
pp. 289-299
Author(s):  
Margaret McCarron ◽  
William Gelbart ◽  
Arthur Chovnick
Keyword(s):  
Drosophila Melanogaster ◽  
Information Transfer ◽  
Large Scale ◽  
Genetic Basis ◽  
Xanthine Dehydrogenase ◽  
Specific Protein ◽  
Wild Type ◽  
Electrophoretic Variation ◽  
The Stability ◽  
Recombination Experiments

ABSTRACT A convenient method is described for the intracistronic mapping of genetic sites responsible for electrophoretic variation of a specific protein in Drosophila melanogaster. A number of wild-type isoalleles of the rosy locus have been isolated which are associated with the production of electrophoretically distinguishable xanthine dehydrogenases. Large-scale recombination experiments were carried out involving null enzyme mutants induced on electrophoretically distinct wild-type isoalleles, the genetic basis for which is followed as a nonselective marker in the cross. Additionally, a large-scale recombination experiment was carried out involving null enzyme rosy mutants induced on the same wild-type isoallele. Examination of the electrophoretic character of crossover and convertant products recovered from the latter experiment revealed that all exhibited the same parental electrophoretic character. In addition to documenting the stability of the xanthine dehydrogenase electrophoretic character, this observation argues against a special mutagenesis hypothesis to explain conversions resulting from allele recombination studies.

scholarly journals Contrasting Histories of Three Gene Regions Associated With In(3L)Payne of Drosophila melanogaster

Genetics ◽  
1996 ◽  
Vol 144 (4) ◽  
pp. 1565-1575 ◽  
Author(s):  
Esteban Hasson ◽  
Walter F Eanes
Keyword(s):  
Drosophila Melanogaster ◽  
Sequence Variation ◽  
Present Report ◽  
Genetic Exchange ◽  
Nucleotide Variation ◽  
Distal Breakpoint ◽  
Esterase 6 ◽  
The Common ◽  
Neutrality Tests ◽  
Hsp83 Gene

In the present report, we studied nucleotide variation in three gene regions of Drosophila melanogaster, spanning >5 kb and showing different degrees of association with the cosmopolitan inversion In(3-L)Payne. The analysis of sequence variation in the regions surrounding the breakpoints and the heat shock 83 (Hsp83) gene locus, located close to the distal breakpoint, revealed the absence of shared polymorphisms and the presence of a number of fixed differences between arrangements, indicating absence of genetic exchange. In contrast, for the esterase-6 gene region, located in the center of the inversion, we observed the presence of shared polymorphisms between arrangements suggesting genetic exchange. In the regions close to the breakpoints, the common St arrangement is 10 times more polymorphic than inverted chromosomes. We propose that the lack of recombination between arrangements in these regions coupled with genetic hitchhiking is the best explanation for the low heterozygosity observed in inverted lines. Using the data for the breakpoints, we estimate that this inversion polymorphism is around 0.36 million yr old. Although it is widely accepted that inversions are examples of balanced polymorphisms, none of the current neutrality tests including our Monte Carlo simulations showed significant departure from neutral expectations.

scholarly journals GENETIC ANALYSIS OF THE CENTROMERIC HETEROCHROMATIN OF CHROMOSOME 2 OF DROSOPHILA MELANOGASTER: DEFICIENCY MAPPING OF EMS-INDUCED LETHAL COMPLEMENTATION GROUPS

Genetics ◽  
1976 ◽  
Vol 83 (4) ◽  
pp. 765-782
Author(s):  
Arthur J Hilliker
Keyword(s):  
Drosophila Melanogaster ◽  
Present Report ◽  
Heterochromatic Region ◽  
Centromeric Heterochromatin ◽  
Genetic Constitution ◽  
Genetic Dissection ◽  
Chromosome 2 ◽  
Multiple Alleles ◽  
Products Analysis ◽  
Dominance Tests

ABSTRACT Until recently, little was known of the genetic constitution of the heterochromatic segments of the major autosomes of Drosophila melanogaster. Our previous report described the genetic dissection of the proximal, heterochromatic region of chromosome 2 of Drosophila melanogasterby means of a series of overlapping deficiencies generated by the detachment of compound second autosomes (Hilliker and Holm 1975). Analysis of these deficiencies by inter se complementation, pseudo-dominance tests with proximal mutations and allelism tests with known deficiencies provided evidence for the existence of at least two loci between the centromere and the light locus in 2L and one locus in 2R between the rolled locus and the centromere. These data in conjunction with cytological observations demonstrated that light and rolled and three loci lying between them are located within the proximal heterochromatin of the second chromosome.——The present report describes the further analysis of this region through the induction with ethyl methanesulphonate (EMS) of recessive lethals allelic to the 2L and 2R proximal deficiencies associated with the detachment products. Analysis of the 118 EMS-induced recessive lethals and visible mutations recovered provided evidence for seven loci in the 2L heterochromatin and six loci in the 2R heterochromatin, with multiple alleles being obtained for most sites. Of these loci, one in 2L and two in 2R fall near the heterochromatic-euchromatic junctions of 2L and 2R respectively. None of the 113 EMS lethals behaved as a deficiency, implying that the heterochromatic loci uncovered in this study represent nonrepetitive cistrons. Thus functional genetic loci are found in heterochromatin, albeit at a very low density relative to euchromatin.

scholarly journals Vertebrate melanophores as potential model for drug discovery and development: A review

2011 ◽  
Vol 16 (1) ◽  
Author(s):  
Saima Salim ◽  
Sharique Ali
Keyword(s):  
Drug Discovery ◽  
High Throughput Screening ◽  
Skin Pigmentation ◽  
Physiological Mechanism ◽  
Pigment Granule ◽  
Pharmaceutical Products ◽  
Surface Receptors ◽  
Pigment Granules ◽  
Intracellular Signals ◽  
Specific Receptors

AbstractDrug discovery in skin pharmacotherapy is an enormous, continually expanding field. Researchers are developing novel and sensitive pharmaceutical products and drugs that target specific receptors to elicit concerted and appropriate responses. The pigment-bearing cells called melanophores have a significant contribution to make in this field. Melanophores, which contain the dark brown or black pigment melanin, constitute an important class of chromatophores. They are highly specialized in the bidirectional and coordinated translocation of pigment granules when given an appropriate stimulus. The pigment granules can be stimulated to undergo rapid dispersion throughout the melanophores, making the cell appear dark, or to aggregate at the center, making the cell appear light. The major signals involved in pigment transport within the melanophores are dependent on a special class of cell surface receptors called G-protein-coupled receptors (GPCRs). Many of these receptors of adrenaline, acetylcholine, histamine, serotonin, endothelin and melatonin have been found on melanophores. They are believed to have clinical relevance to skin-related ailments and therefore have become targets for high throughput screening projects. The selective screening of these receptors requires the recognition of particular ligands, agonists and antagonists and the characterization of their effects on pigment motility within the cells. The mechanism of skin pigmentation is incredibly intricate, but it would be a considerable step forward to unravel its underlying physiological mechanism. This would provide an experimental basis for new pharmacotherapies for dermatological anomalies. The discernible stimuli that can trigger a variety of intracellular signals affecting pigment granule movement primarily include neurotransmitters and hormones. This review focuses on the role of the hormone and neurotransmitter signals involved in pigment movement in terms of the pharmacology of the specific receptors.

scholarly journals Protein kinase C activation antagonizes melatonin-induced pigment aggregation in Xenopus laevis melanophores.

1992 ◽  
Vol 119 (6) ◽  
pp. 1515-1521 ◽  
Author(s):  
D Sugden ◽  
S J Rowe
Keyword(s):  
Protein Kinase C ◽  
Protein Kinase ◽  
Xenopus Laevis ◽  
Pigment Granule ◽  
Melatonin Receptors ◽  
Kinase C ◽  
Pigment Granules ◽  
Slow Aggregation ◽  
Pigment Aggregation ◽  
Induced Aggregation

The pineal hormone, melatonin (5-methoxy N-acetyltryptamine) induces a rapid aggregation of melanin-containing pigment granules in isolated melanophores of Xenopus laevis. Treatment of melanophores with activators of protein kinase C (PKC), including phorbol esters, mezerein and a synthetic diacylglycerol, did not affect pigment granule distribution but did prevent and reverse melatonin-induced pigment aggregation. This effect was blocked by an inhibitor of PKC, Ro 31-8220. The inhibitory effect was not a direct effect on melatonin receptors, per se, as the slow aggregation induced by a high concentration of an inhibitor of cyclic AMP-dependent protein kinase (PKA), adenosine 3',5'-cyclic monophosphothioate, Rp-diastereomer (Rp-cAMPS), was also reversed by PKC activation. Presumably activation of PKC, like PKA activation, stimulates the intracellular machinery involved in the centrifugal translocation of pigment granules along microtubules. alpha-Melanocyte stimulating hormone (alpha-MSH), like PKC activators, overcame melatonin-induced aggregation but this response was not blocked by the PKC inhibitor, Ro 31-8220. This data indicates that centrifugal translocation (dispersion) of pigment granules in Xenopus melanophores can be triggered by activation of either PKA, as occurs after alpha-MSH treatment, or PKC. The very slow aggregation in response to inhibition of PKA with high concentrations of Rp-cAMPS, suggests that the rapid aggregation in response to melatonin may involve multiple intracellular signals in addition to the documented Gi-mediated inhibition of adenylate cyclase.

scholarly journals DNA replication of histone gene repeats in Drosophila melanogaster tissue culture cells: multiple initiation sites and replication pause sites.

1993 ◽  
Vol 13 (7) ◽  
pp. 4098-4106 ◽  
Author(s):  
T Shinomiya ◽  
S Ina
Keyword(s):  
Tissue Culture ◽  
Drosophila Melanogaster ◽  
Dna Replication ◽  
Present Report ◽  
Polymerase Chain Reaction Method ◽  
Mapping Method ◽  
Histone Gene ◽  
Culture Cells ◽  
Tissue Culture Cells ◽  
Replication Intermediates

We showed previously that DNA replication initiates at multiple sites in the 5-kb histone gene repeating unit in early embryos of Drosophila melanogaster. The present report shows evidence that replication in the same chromosomal region initiates at multiple sites in tissue culture cells as well. First, we analyzed replication intermediates by the two-dimensional gel electrophoretic replicon mapping method and detected bubble-form replication intermediates for all fragments restricted at different sites in the repeating unit. Second, we analyzed bromodeoxyuridine-labeled nascent strands amplified by the polymerase chain reaction method and detected little differences in the size distribution of nascent strands specific to six short segments located at different sites in the repeating unit. These results strongly suggest that DNA replication initiates at multiple sites located within the repeating unit. We also found several replication pause sites located at 5' upstream regions of some histone genes.

scholarly journals Inherited dysfunctional platelet P2Y12 receptor mutations associated with bleeding disorders

2016 ◽  
Vol 36 (04) ◽  
pp. 279-283 ◽  
Author(s):  
Anna Lecchi ◽  
Eti Femia ◽  
Silvia Paoletta ◽  
Arnaud Dupuis ◽  
Philippe Ohlmann ◽  
...  
Keyword(s):  
Conformational Changes ◽  
Structural Integrity ◽  
Present Report ◽  
Critical Role ◽  
Receptor Expression ◽  
Severe Bleeding ◽  
Modelling Studies ◽  
Agonist And Antagonist ◽  
High Concentrations

SummaryThe platelet adenosine 5’-diphosphate (ADP) receptor P2Y12 (P2Y12R) plays a critical role in platelet aggregation. The present report illustrates an update of dysfunctional platelet P2Y12R mutations diagnosed with congenital lifelong bleeding problems. Described patients with heterozygous or homozygous substitution in the P2Y12R gene and qualitative abnormalities of the platelet P2Y12R are summarized. Recently, a further dysfunctional variant of P2Y12R has been identified in two brothers who presented with a lifelong severe bleeding disorder. During in vitro aggregation studies, the patient´s platelets show a markedly reduced and rapid reversible ADP-promoted aggregation. A homozygous c.561T>A substitution that changes the codon for His187 to Gln (p.His187Gln) in the P2Y12R gene has been identified. This mutation causes no change in receptor expression but decreases the affinity of the ligand for the receptor, even at high concentrations. Structure modelling studies indicated that the p.His187Gln mutation, located in the fifth transmembrane spanning domain (TM5), impairs conformational changes of the receptor. Structural integrity of the TM5 region is necessary for agonist and antagonist binding and for correct receptor function.

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